Weft thread monitoring system in a circular loom

ABSTRACT

A device for monitoring a weft in a circular loom where the weft is drawn-off from a bobbin of the weaving shuttle rotating along a circular path formed by a circular reed. The device includes a magnetic sensor stationarily arranged in a zone of the circular path of the weaving shuttle for generating an electronic control signal to turn off the loom when there is a fault in the weft creating an operative connection between the magnetic sensor and a permanent magnet. The magnet is carried by the weaving shuttle. The device has a pivoting lever having the permanent magnet arranged thereon. The device also includes a return spring that displaces the pivoting lever as well as the permanent magnet attached thereon towards a position where the operative connection between the magnetic sensor and the permanent magnet is made. During the normal operation of the circular loom, the weft being drawn-off holds the permanent magnet against the influence of the return spring outside of the position where the operative connection is made.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a device for monitoring wefts in acircular loom which are wound off from the respective bobbin of theweaving shuttles rotating in the weaving shed along a circular pathformed by the circular reed and are delivered to the fabric edge of thewoven hose, whereby a scanning means monitors the respective weft inorder to generate an electric control signal in case of a weft fault.

2. Description of Prior Art

Circular looms are generally known in which a plurality of sectionalshafts are arranged in a circular way around the circular reed of themachine and each carry a plurality of inner and outer harnesses forguiding a part of the two circularly distributed warp assemblages whichare subjected to an opposing upwardly and downwardly alternate movementfor forming the weaving or walking shed via a rotating main shaft. Theweaving shuttles rotatingly driven by the main shaft in the circularreed deliver the weft to be drawn off from the respectively entrainedbobbin continuously to the walking shed. The woven hose thus produced isthen drawn off and wound up as a flat circular fabric.

In this respect it is essential that the proper presence of the wefts tobe drawn off from the bobbins of the rotating shuttles is monitored ascarefully as possible in order to control the machine in a respectiveway for preventing weaving faults, e.g. by turning it off immediately incase of weft faults which may be caused by breakage of the weft orexhaustion of the weft bobbin.

Known devices of this kind use, among other things, photooptical sensingelements in which the photocell is activated by a reflecting surfacepivoting into the light beam. Such light barriers, however, can nolonger meet current requirements, particularly in view of theconsiderably increased revolving speeds of the weaving shuttles and thegeneration of precise control signals.

Light barriers have always been susceptible to influences by externallight, become easily dusty and do not allow any processing of reflexribbons owing to "blinding".

SUMMARY OF THE INVENTION

It is thus the object of the present invention to provide a device formonitoring the wefts in a circular loom which is not subject to thedisadvantages of the known state of the art.

This is achieved at first in accordance with the invention in that theelectric control signal is producable by a magnetic sensor which isarranged in the zone of the revolving path of the weaving shuttles andwhich cooperates with a permanent magnet carried by the respectiveweaving shuttle, whereby the permanent magnet is arranged on a pivotinglever deflected by the drawn-off weft against the effect of spring-likereturn means and is held outside of the operative connection with themagnetic sensor in order to reach, in case of a weft fault, under theinfluence of the return means its end position producing an operativeconnection of the permanent magnet with the magnetic sensor forgenerating an active control signal.

Such a device is neither subject to any influence by external light, norto any malfunctions through dust accumulation or to any wear and tear.This device, however, allows the processing of reflex ribbons, workssecurely at any revolving speed of the shuttles and is provided with avery high response sensitivity and response speed.

In order to reduce the revolving path of the affected shuttle with itspermanent magnet to the magnetic sensor to a few angular degrees it isadvantageous to arrange on the reed or the like a plurality of suchmagnetic sensors distributed over the circumferential direction.

A simple and functionally entirely secure arrangement can be achievedfurthermore in that the pivoting lever carrying the permanent magnet atits free end is arranged with its pivoting axle on the thread insertionapparatus of the shuttle and is under the influence of a return spring,whereby the drawn-off weft penetrates or at least partly wraps around anend section at the free end of the pivoting lever or that the pivotinglever carrying the Permanent magnet at its free end is arranged with itspivoting axle on the rotational axle of the weft bobbin and is under theinfluence of a return spring, whereby the drawn-off weft penetrates orat least partly wraps around an end section at the free end of thepivoting lever.

Exemplified embodiments of the subject matter of the invention areexplained below by reference to the drawings.

BREIF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a circular loom in a side view and in a schematicrepresentation;

FIG. 2 shows a partial view of a weaving shuttle with the device inaccordance with the invention for monitoring the wefts of thearrangement in accordance with FIG. 1 on an enlarged scale, and

FIG. 3 shows a partial top view of a weaving shuttle with the device inaccordance with the invention for monitoring the wefts of thearrangement in accordance with FIG. 1 on an enlarged scale, and

FIG. 4 shows an embodiment of the arrangement in accordance with FIGS. 2and 3 in a side view and on an enlarged scale.

DETAILED DESCRIPTION OF THE PERFERRED EMBOBIMENTS

The circular loom in accordance with FIG. 1 rests in the usual manner onthe basic frame 1 of the machine, on which a circular frame carrier 2rests, which carries the circular reed 3, the "on" and "off" button 4for the machine and furthermore frame parts 5 for supporting the shafts6. These shafts 6 are arranged in the known way around the main shaft 8of the machine and form to a substantial extent the shed-forming meansof the machine. The fabric draw-off apparatus rests further on basicframe 1 of the carriers 9, which is indicated herein only by fabricdraw-off rollers 10. A fabric expander 14 is also effective in thedraw-off zone. The drawing further shows in the circular loom thedrawing-in roller 15 for the ends on the left and the drawing-in rollers16 for the ends on the right. Said ends 7, whose course is onlyindicated, are divided into two circularly arranged warp assemblages andare drawn off in the known way by groups of warp bobbins (not shown incloser detail). For forming the weaving shed one of these assemblages isthen lifted, whereas the other is guided from the level of the weavingplane downwardly through the so-called shed changing movements, so thata warp thread upper shed 7' and a warp thread lower shed 7" arises(FIGS. 2 and 4). In this so-called weaving or walking shed at least one,but usually several shuttles 30 with a weft bobbin 31 (FIG. 4) revolveon a horizontal circular path. As a result of the circular movement ofthe shuttles, the weft 32 (FIGS. 2, 3 and 4) wound off from the weftbobbin is delivered to the fabric edge 13 of the produced woven hose, sothat said weft can be weaved into the fabric. The woven hose can then bedrawn off upwardly and can be laid into a flat circular fabric.

To this point the arrangement of the circular loom as outlined above cancoincide with the known state of the art, so that any furtherexplanation of such a machine can be omitted.

The problem to be treated herein in such a circular loom consists ofmonitoring as carefully and functionally secure as possible the wefts 32drawn off from the bobbins 31 of the revolving shuttles 30 in order tobe able to control the machine accordingly by means of a generatedcontrol signal 23 in case of a weft fault.

It is provided in accordance with the invention for this purpose thatthe electric control signal 23 can be generated by a magnetic sensor 22arranged in the zone of the revolving path of the weaving shuttles 30,which sensor cooperates with a permanent magnet 24 carried by therespective weaving shuttle 30. The permanent magnet is arranged on apivoting lever 26 deflected by the drawn-off weft 32 against the effectof spring-like return means 25 and is held outside of the operativeconnection with the magnetic sensor in order to reach, in case of a weftfault, under the influence of the return means 25 its end positionproducing an operative connection of the permanent magnet with themagnetic sensor for generating an active control signal 23.

It is further provided to arrange in the zone of the revolving path ofthe weaving sheds, preferably on reed 3, a plurality of magnetic sensors22, as is indicated in FIG. 1.

As is shown in FIGS. 2 and 3 in closer detail, the pivoting lever 26carrying the permanent magnet 24 at its free end is arranged with itspivoting axle 27 on the thread insertion apparatus 30' on the shuttle 30and is under the influence of a return spring 25, whereby the drawn-offweft penetrates an end section at the free end of pivoting lever 26 orwraps around it at least partially.

Alternatively in accordance with FIG. 4, the pivoting lever 26' carryingthe permanent magnet 24' at its free end can be arranged with itspivoting axle 27' on the rotational axle of the weft bobbin 31 and beunder the influence of a return spring 25', whereby here too thedrawn-off weft penetrates an end section at the free end of pivotinglever 26' or wraps around it at least partially.

Where the circular loom includes several shuttles as described above,the circular loom includes a plurality of permanent magnets 24 which areassociated with and carried by the plurality of weaving shuttles 30 anda plurality levers 26 on which said plurality of permanent magnets 24are arranged. Each of the plurality of pivoting levers carries theplurality of permanent magnets at its free end.

The above results in a device in accordance with the invention formonitoring the wefts in a circular loom which meets all the requirementsas mentioned above. In particular, the aforementioned measures allow aneasy conversion of already existing machines as well as the use of weftmonitoring devices in other thread-processing machines.

It is understood that modifications can be made to the device mentionedabove without departing from the inventive idea, in particular thepivoting lever can be returned also under the influence of its ownweight or the centrifugal force.

What is claimed is:
 1. A circular loom having a device for monitoringwefts, said circular loom comprising:a weaving shed; a circular reedlocated in said weaving shed and forming a circular path; a plurality ofweaving shuttles which rotate along said circular path; a plurality ofbobbins associated with said weaving shuttles, each of the wefts beingwound off from a respective one of said plurality of bobbins and beingdelivered to a fabric edge of a woven hose; a scanner which monitors thewefts in order to generate an electronic control signal in case of aweft fault, said scanner including:a magnetic sensor which generatessaid electronic control signal and which is stationarily arranged in azone of said circular path of said plurality of weaving shuttles; aplurality of permanent magnets which are associated with and carried bysaid plurality of weaving shuttles, a plurality of pivoting levers onwhich said plurality of permanent magnets are arranged; and a pluralityof return springs configured to move said plurality of pivoting levers,wherein said plurality of pivoting levers are deflected by the weftsbeing drawn-off against an effect of said plurality of return springsand said plurality of permanent magnets are held outside of an operativeconnection with said magnetic sensor, and when in case of a weft faultsaid effect of said plurality of return springs causes at least one ofsaid plurality of permanent magnets to displace to an end position ofsaid plurality of permanent magnets producing said operative connectionof at least one of said plurality of permanent magnets with saidmagnetic sensor for generating said electric control signal.
 2. Acircular loom as defined in claim 1, further comprising a plurality ofmagnetic sensors, said plurality of magnetic sensors being equallyspaced along said zone of said circular path of said plurality ofweaving shuttles.
 3. A circular loom as defined in claim 1, wherein eachof said plurality of pivoting levers include a free end, an end sectionand a pivoting axle, and each of said plurality of weaving shuttlesinclude a thread insertion apparatus,wherein each of said plurality ofpivoting levers carries said plurality of permanent magnets at said freeend and is arranged with said pivoting axle on said thread insertionapparatus and is under said effect of said plurality of return springs,wherein each of the wefts being drawn-off penetrates said end section atsaid free end of each of said plurality of pivoting levers.
 4. Acircular loom as defined in claim 1, wherein each of said plurality ofpivoting levers include a free end, an end section and a pivoting axle,and each of said plurality of weaving shuttles include a threadinsertion apparatus,wherein each of said plurality of pivoting leverscarries said plurality of permanent magnets at said free end and isarranged with said pivoting axle on said thread insertion apparatus andis under said effect of said plurality of return springs, wherein eachof the wefts being drawn-off partly wraps around said end section atsaid free end of each of said plurality of pivoting levers.
 5. Acircular loom as defined in claim 1, wherein each of said plurality ofpivoting levers include a free end, an end section and a pivoting axle,and each of said plurality of bobbins include a rotational axle,whereineach of said plurality of pivoting levers carries said plurality ofpermanent magnets at said free end and is arranged with said pivotingaxle on said rotational axle and is under said effect of said pluralityof return springs, wherein each of the wefts being drawn-off penetratessaid end section at said free end of each of said plurality of pivotinglevers.
 6. A circular loom as defined in claim 1, wherein each of saidplurality of pivoting levers include a free end, an end section and apivoting axle, and each of said plurality of bobbins include arotational axle,wherein each of said plurality of pivoting leverscarries said plurality of permanent magnets at said free end and isarranged with said pivoting axle on said rotational axle and is undersaid effect of said plurality of return springs, wherein each of thewefts being drawn-off partly wraps around said end section at said freeend of each of said plurality of pivoting levers.
 7. A device formonitoring a weft in a circular loom, the weft being drawn-off from abobbin of a weaving shuttle having a thread insertion apparatus androtating along a circular path formed by a circular reed, saidmonitoring device comprising:a pivoting lever having a free end and anend section adapted to be penetrated by the weft being drawn-off, saidpivoting lever being adapted to be pivotally connected to the threadinsertion apparatus of the weaving shuttle; a permanent magnet, saidpermanent magnet being carried by said pivoting lever at said free end;a return spring having an influence to displace said pivoting levertowards an end position; and a magnetic sensor stationarily arranged ina zone of the circular path of the weaving shuttle for generating anelectronic control signal to turn off the loom when there is a fault inthe weft creating an operative connection with said permanent magnet,wherein said permanent magnet is held outside of said operativeconnection by the weft being drawn-off against said influence of saidreturn spring, and when there is a fault in the weft said influence ofsaid return spring causes said pivoting lever to displace to said endposition whereby said permanent magnet creates said operative connectionwith said magnetic sensor.
 8. A device for monitoring a weft in acircular loom as defined in claim 7, further comprising a plurality ofmagnetic sensors, said plurality of magnetic sensors being equallyspaced along the zone of the circular path of the weaving shuttle.
 9. Adevice for monitoring a weft in a circular loom, the weft beingdrawn-off from a bobbin of a weaving shuttle having a thread insertionapparatus and rotating along a circular path formed by a circular reed,said monitoring device comprising:a pivoting lever having a free end andan end section adapted to be partly wrapped around by the weft beingdrawn-off, said pivoting lever being adapted to be pivotally connectedto the thread insertion apparatus of the weaving shuttle; a permanentmagnet, said permanent magnet being carried by said pivoting lever atsaid free end; a return spring having an influence to displace saidpivoting lever towards an end position; and a magnetic sensorstationarily arranged in a zone of the circular path of the weavingshuttle for generating an electronic control signal to turn off the loomwhen there is a fault in the weft creating an operative connection withsaid permanent magnet, wherein said permanent magnet is held outside ofsaid operative connection by the weft being drawn-off against saidinfluence of said return spring, and when there is a fault in the weftsaid influence of said return spring causes said pivoting lever todisplace to said end position whereby said permanent magnet creates saidoperative connection with said magnetic sensor.
 10. A device formonitoring a weft in a circular loom as defined in claim 9, furthercomprising a plurality of magnetic sensors, said plurality of magneticsensors being equally spaced along the zone of the circular path of theweaving shuttle.
 11. A device for monitoring a weft in a circular loom,the weft being drawn-off from a bobbin of a weaving shuttle rotatingalong a circular path formed by a circular reed, the bobbin having arotational axle, said monitoring device comprising:a pivoting leverhaving a free end and an end section adapted to be penetrated by theweft being drawn-off, said pivoting lever being adapted to be pivotallyconnected to the rotational axle of the weft bobbin of the weavingshuttle; a permanent magnet, said permanent magnet being carried by saidpivoting lever at said free end; a return spring having an influence todisplace said pivoting lever towards an end position; and a magneticsensor stationarily arranged in a zone of the circular path of theweaving shuttle for generating an electronic control signal to turn offthe loom when there is a fault in the weft creating an operativeconnection with said permanent magnet, wherein said permanent magnet isheld outside of said operative connection by the weft being drawn-offagainst said influence of said return spring, and when there is a faultin the weft said influence of said return spring causes said pivotinglever to displace to said end position whereby said permanent magnetcreates said operative connection with said magnetic sensor.
 12. Adevice for monitoring a weft in a circular loom as defined in claim 11,further comprising a plurality of magnetic sensors, said plurality ofmagnetic sensors being equally spaced along the zone of the circularpath of the weaving shuttle.
 13. A device for monitoring a weft in acircular loom, the weft being drawn-off from a bobbin of a weavingshuttle rotating along a circular path formed by a circular reed, thebobbin having a rotational axle, said monitoring device comprising:apivoting lever having a free end and end section adapted to be partlywrapped around by the weft being drawn-off, said pivoting lever beingadapted to be pivotally connected to the rotational axle of the weftbobbin of the weaving shuttle; a permanent magnet, said permanent magnetbeing carried by said pivoting lever at said free end; a return springhaving an influence to displace said pivoting lever towards an endposition; and a magnetic sensor stationarily arranged in a zone of thecircular path of the weaving shuttle for generating an electroniccontrol signal to turn off the loom when there is a fault in the weftcreating an operative connection with said permanent magnet, whereinsaid permanent magnet is held outside of said operative connection bythe weft being drawn-off against said influence of said return spring,and when there is a fault in the weft said influence of said returnspring causes said pivoting lever to displace to said end positionwhereby said permanent magnet creates said operative connection withsaid magnetic sensor.
 14. A device for monitoring a weft in a circularloom as defined in claim 13, further comprising a plurality of magneticsensors, said plurality of magnetic sensors being equally spaced alongthe zone of the circular path of the weaving shuttle.